Nickel Iron Batteries real data

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T1 Terry
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Real Name: Terry Covill
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Re: Nickel Iron Batteries real data

Post by T1 Terry »

paulvk wrote: Mon, 26 Oct 2020, 07:35 It is an important step and I can not see why it is not in the present manufactures instructions.
I have two cell going through another 12 hour charge these were the first to drop below 1 volt on the last discharge test
but I did get more than 100Ah out of them problem is its wet and cloudy for the next week so not much I can do,
do not want to use the grid for the whole 12 hours!

If MPP Solar were more responsive I could work with them to get an inverter to work with NiFe/NiCad.
I think if I had a victron unit they might have worked with me but they are just so way more expensive.
Also there seems to be no SCC unit capable of charging NiFe/NiCad as the voltage range is 44v to 72v
for a 48v battery, the Esmart-3 I have only does it because of a design flaw, the software max volts
is above the capability of the hardware to report so while I can set the software to 60 volts
the hardware can only get to 58 volts so it just keeps charging getting to 64 volts with
38 cells and its max capability of 40 amps note the current sensing works ok so it limits to 40 amps.

I do not like using a Pi for tasks like this way too much code running that is unnecessary.
MPP Solar make a 60 amp MPPT controller called a PCM60X and it has separate voltage sensing cables. By using a voltage reducing circuit and run through a mini DPDT relay driven by the cell voltage sensing to switch when a cell goes high voltage, the reduced votage can be sent to the voltage sensing section of the PCMX60 so it contues to charge up to what ever voltage you are looking for, then switching the realy to send battery voltage to the sensing wires to stop the charging when required.

T1 Terry
Green but want to learn
paulvk
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Re: Nickel Iron Batteries real data

Post by paulvk »

The PCM60X is the MPPT charger that is in the inverters I have but even as a separate charger 62v is still too low, if I was to have
40 cells its 1.6v x 40 68v and for the 30 min charge of 1.8v its 72v so with 38 cells 60v and 68v . With NiFe or NiCad the voltage range
can be from 44v to 70v which is a large difference so there is not an inverter that is designed to work over this range but I can not
let my inverters see this swing so the Esmart3 disconnects the NiFe's when it gets to 56v and keeps going and gets them to 63v
while the chargers in in the inverters keep the lead acid banks charged and run the loads Now when the NiFe bank comes back on load
when the voltage drops to 56v they supply all power and put a small charge into the lead acid bank when this stabilizes I have the
lead acid floating supplying no power with the NiFe's discharging this is minimizing the lead acid cycles.
Note the esmart3 can not measure above 58v but has a 60v (15v x 4) setting so it thinks its got to keep charging which works for me.
Also I changed the 63v capacitors on the battery side of the esmart to 80v used the same ones that replace those in the inverters.
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